Category: AngularJS

We get to work on some great projects here at thinkWhere, but we’re particularly proud of the project we’ve just started with the Humanitarian OpenStreetMap Team (HOT) to develop the Tasking Manager version 3.0 (TM3). It’s great to work in an industry where the work we do with maps can have such a tangible impact on the humanitarian effort. thinkWhere support this wherever we can by supporting MapAction by both supporting my own personal volunteering (which you can read more about here) and through fundraising efforts such the running the Stirling Marathon, which is open for sponsorship here so please donate if you can! Therefore being given the opportunity to also get involved with the HOT Community and deliver TM3 is something we’re extremely proud of.

The current HOT Tasking Manager (TM2) coordinates volunteer mapper contribution to OpenStreetMap, meaning the global network of HOT volunteers can map affected areas efficiently providing disaster responders on the ground such as MapAction, MSF and the Red Cross access to detailed mapping during the response.

Following a significant increase in the capture of OSM data through initiatives such as Missing Maps, and subsequent loads on existing servers and software, the development of TM3 aims to better meet the needs of mappers, validators and project managers. This will be achieved by taking advantage of the very latest advances and innovations in web development frameworks and methodologies.

“We are very excited to be working with thinkWhere to develop the next generation of HOT’s Tasking Manager application. The team at thinkWhere brings a wealth of geospatial development experience, talent and insight to the project. Used by thousands of people around the world, our Tasking Manager software is the key technology component that enables our humanitarian mapping work and having thinkWhere as partners ensures the development project will be a success and deliver a great result for our community”.

In early February 2017, we travelled to HOT’s office in Washington DC for the project initiation meeting with various project stakeholders to discuss initial requirements and wireframe designs.

This engagement with some of the largest users of the Tasking Manager to discuss functionality and solicit feedback on how features might be implemented was a great way to start the project. A long, but very productive day, the discussion involved representatives from Missing Maps, YouthMappers, TeachOSM, GeoCenter, the US State Department’s Humanitarian Information Unit, Mapbox, HOT Project Managers, American Red Cross and Ethan Nelson, the lead community development volunteer.

thinkWhere’s Chief Executive Alan Moore said…

“We’re really delighted and privileged to be working with the team at HOT. Redevelopment of the Tasking Manager will be key to the future growth and sustainability of the humanitarian mapping effort across the world. The development work flows naturally from the innovative work we’ve been doing recently on theMapCloud, our new spatial data platform, and we’re keen to bring those advantages to the benefit of HOT and the global mapping community”.

Intro

We’ve recently released a new product called mapTrunk. The app is built using the open source libraries AngularJS and OpenLayers 3 (among many others!). As part of our development efforts we looked into creating reusable modules. This blog post offers a high level introduction to AngularJS and OpenLayers 3 and shows how they can work together to create a reusable map scale bar module example.

AngularJS and OpenLayers 3

AngularJS is an open source JavaScript framework for creating web apps. It provides tools for making apps modular. AngularJS handles binding data which means the view (HTML) automatically updates when the model (JavaScript) updates. Other benefits of AngularJS include form validation in the browser, the ease of wiring an app up to a backend and the testability of the code. AngularJS also lets you extend the syntax of HTML and inject components into your HTML. This feature comes in handy when creating the scale bar module.

OpenLayers 3 is an open source mapping library. It provides tools for adding dynamic maps to an app. Commonly used mapping controls provided by OpenLayers include zooming in/out control, a mouse position control and a scale bar control.

The following example shows how to create a basic map with OpenLayers and AngularJS. The result is a map and a button to recenter the map. It also shows the user how many times they have centred the map.

HTML

Firstly we need to include the AngularJS and OpenLayers 3 libraries, add a div for the map and add a button. We also need to include the Angular app called “app”, which is created in JavaScript.

Creating the scale bar module

The OpenLayers library already has a scale bar module called ‘scale line’ built-in. An example can be found here. One of the requirements for mapTrunk was to create a scale line that can display distances in two units at the same time, metric and imperial.

To create a reusable module we can create a custom Angular directive. Angular directives basically let us create our own HTML syntax and inject components by using that HTML syntax. It makes the HTML code easier to read and hides the complexity of the component. In this blog we’re not going to go into the details of Angular directives so please see AngularJS’s documentation on directives for a full explanation.

First we need to create the Angular directive and decide what the HTML syntax is going to be. In the code snippet below we called the directive scaleLineControl. This translates into the HTML tag . The directive needs to have access to an OpenLayers map object to be able to add a scale line control to the map. The map object can be passed into the directive by adding it as a property to the HTML ‘map=”main.map”‘. The OpenLayers scale line control needs a HTML target ID so this ID can be given to the HTML directive as well. The scale line control is added to the OpenLayers map object by using the addControl function. The units of the first control are specified as metric. To create a scale line module which also shows imperial measurements, a second scale line control is added to the map with imperial units. OpenLayers takes care of listening out for changes on the map and updates the controls accordingly. Now we should see two scale lines on the map, but they are positioned on top of each other so we need some CSS to fix this.

Making it look good!

We can specify the CSS class names when creating the OpenLayers scale line controls. By doing so we can customise the default look of the scale line controls. Here we have added the class ‘scale-line-top’ to the metric control and ‘scale-line-bottom’ to the imperial control.